Daunted by the prospect of 19 female classmates, kindergartener John Hercules Po is determined to turn them into tomboys. From the first day at recess, John seizes upon what he considers a suitably boyish endeavor. The girls happily play along, but not without adding their own unique contribution to the game. With his older brother pressuring him not turn into a “sissy,” John struggles with the enormous fun he has each day, along with his concern of how others perceive him. Pattison perfectly captures this awkward stage during which young children struggle to define their roles and by week’s end, John no longer identifies his classmates as girls, but as friends. Salerno’s ink-and-watercolor illustrations are wonderfully imaginative. Through using the contrast of grayish hues for the school-related pictures with the intense color burst of the recess illustrations, he conveys the uplifting sense of freedom the children experience when they surrender themselves to play. Pattison’s adept and amusing depiction of this early battle between the sexes and her harmonious solution is ideal for readers of any gender. (Picture book. 4-8)